This invention relates to seismic exploration and more particularly, to the deconvolution of seismic traces to remove noise and distortion.
In seismic exploration, it has become common to process the seismic traces obtained as a result of a seismic disturbance to remove some of the noise thereby rendering the seismic data easier to interpret.
The noise which is present in the seismic traces may include random, or incoherent, noise which is present by reason of the instruments used or the particular obscuring nature of the geophysical formations being surveyed.
There is another type of noise which is referred to as coherent noise. This noise includes what is commonly referred to as ghosts or multiple reflections from the reflecting interfaces. Other coherent noise includes noise trains and near surface refractions.
In seismic exploration, the field records include seismic traces from a plurality of detectors located along a line of exploration. When a source of seismic energy is energized, the detectors produce the field records representing the reflections of seismic energy from the subsurface interfaces. However, the traces also include the aforementioned coherent noise. As is well known, the reflections have a moveout from trace to trace which is dependent upon the offset between the seismic detectors and upon the velocity characteristics of the earth. The coherent noise has a different moveout than the reflections.
Examples of techniques which makes use of the different moveout between coherent noise and reflections to filter out the coherent noise as shown in U.S. Pat. Nos. 3,284,763--Burg et al. and 3,550,073--Foster et al.
Inverse filtering, or deconvolution, is an effective technique of removing coherent noise. Once the characteristics of the noise are determined, the operator of a time domain filter which will remove that noise is obtained. U.S. Pat. No. 3,689,874--Foster et al. is an example of deconvolution where the nature of the noise in a seismic trace is determined from the trace itself. An inverse filter then removes that noise from the trace. The present invention is an improvement on this type of process.